// random.h

/*    Copyright 2012 10gen Inc.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

#ifndef TB_UTIL_RANDOM_H__
#define TB_UTIL_RANDOM_H__

#include <cstdint>

#include "utils_export.hpp"

TB_NAMESPACE_BEGIN

/**
    * Uses http://en.wikipedia.org/wiki/Xorshift
    */
class PseudoRandom {
  public:
	PseudoRandom( int32_t seed );

  PseudoRandom( uint32_t seed );

  PseudoRandom( int64_t seed );

  int32_t nextInt32();

  int64_t nextInt64();

  /**
  * @return a number between 0 and max
  */
  int32_t nextInt32( int32_t max ) { return nextInt32() % max; }

  /**
  * @return a number between 0 and max
  */
  int64_t nextInt64( int64_t max ) { return nextInt64() % max; }

  /**
  * @return a number between 0 and max
  *
  * This makes PsuedoRandom instances passable as the third argument to std::random_shuffle
  */
  intptr_t operator()(intptr_t max) {
      if (sizeof(intptr_t) == 4)
          return static_cast<intptr_t>(nextInt32(static_cast<int32_t>(max)));
      return static_cast<intptr_t>(nextInt64(static_cast<int64_t>(max)));
  }

private:
    int32_t _x;
    int32_t _y;
    int32_t _z;
    int32_t _w;
};

/**
    * More secure random numbers
    * Suitable for nonce/crypto
    * Slower than PseudoRandom, so only use when really need
    */
class SecureRandom {
public:
  virtual ~SecureRandom();

  virtual int64_t nextInt64() = 0;

  static SecureRandom* create();
};

TB_NAMESPACE_END

#endif //TB_UTIL_RANDOM_H__
